Mussaurus (meaning "mouse lizard") was an early, plant-eating prosauropoddinosaur from the Upper Triassic, about 215 million years ago. It was found in southern Argentina. It gets its name from the small size of the skeletons first discovered. They were large-eyed hatchlings (babies), only 9-16 inches long (18-37 cm); these are the smallest dinosaur skeletons yet found.

However, Mussaurus is now known from adult specimens.[1] the name is something of a misnomer; adults possibly reached 3 m (10 ft) in length, and weighed 70 kilograms (150 lb).[2]Mussaurus possesses anatomical features suggesting a close, possibly transitional evolutionary relationship with true sauropods.